{
  "title": "Addition and Subtraction - 4-Digit Addition",
  "total_questions": 60,
  "questions": [
    {
      "id": 1,
      "difficulty": "Easy",
      "question": "2000 + 3000 = ?",
      "options": { "A": "4000", "B": "5000", "C": "6000", "D": "3000" },
      "correct_answer": "B"
    },
    {
      "id": 2,
      "difficulty": "Easy",
      "question": "1200 + 1300 = ?",
      "options": { "A": "2400", "B": "2500", "C": "2600", "D": "2300" },
      "correct_answer": "B"
    },
    {
      "id": 3,
      "difficulty": "Easy",
      "question": "1500 + 1400 = ?",
      "options": { "A": "2900", "B": "2800", "C": "3000", "D": "2700" },
      "correct_answer": "A"
    },
    {
      "id": 4,
      "difficulty": "Easy",
      "question": "1000 + 2500 = ?",
      "options": { "A": "2400", "B": "3300", "C": "3500", "D": "3000" },
      "correct_answer": "C"
    },
    {
      "id": 5,
      "difficulty": "Easy",
      "question": "2100 + 1200 = ?",
      "options": { "A": "3100", "B": "3200", "C": "3300", "D": "3000" },
      "correct_answer": "C"
    },
    {
      "id": 6,
      "difficulty": "Easy",
      "question": "1800 + 1100 = ?",
      "options": { "A": "2800", "B": "2900", "C": "2700", "D": "2600" },
      "correct_answer": "B"
    },
    {
      "id": 7,
      "difficulty": "Easy",
      "question": "900 + 2400 = ?",
      "options": { "A": "3100", "B": "3200", "C": "3300", "D": "3000" },
      "correct_answer": "C"
    },
    {
      "id": 8,
      "difficulty": "Easy",
      "question": "1700 + 1300 = ?",
      "options": { "A": "2900", "B": "3000", "C": "3100", "D": "2800" },
      "correct_answer": "B"
    },
    {
      "id": 9,
      "difficulty": "Easy",
      "question": "2200 + 2700 = ?",
      "options": { "A": "4800", "B": "4900", "C": "5000", "D": "5300" },
      "correct_answer": "B"
    },
    {
      "id": 10,
      "difficulty": "Easy",
      "question": "1400 + 1400 = ?",
      "options": { "A": "2600", "B": "2800", "C": "2400", "D": "3000" },
      "correct_answer": "B"
    },
    {
      "id": 11,
      "difficulty": "Easy",
      "question": "2000 + 1800 = ?",
      "options": { "A": "3600", "B": "3700", "C": "3800", "D": "3900" },
      "correct_answer": "C"
    },
    {
      "id": 12,
      "difficulty": "Easy",
      "question": "3000 + 1500 = ?",
      "options": { "A": "4400", "B": "4500", "C": "4600", "D": "4700" },
      "correct_answer": "B"
    },
    {
      "id": 13,
      "difficulty": "Easy",
      "question": "1100 + 1100 = ?",
      "options": { "A": "2100", "B": "2200", "C": "2300", "D": "2000" },
      "correct_answer": "B"
    },
    {
      "id": 14,
      "difficulty": "Easy",
      "question": "2500 + 500 = ?",
      "options": { "A": "2900", "B": "3000", "C": "3100", "D": "2600" },
      "correct_answer": "B"
    },
    {
      "id": 15,
      "difficulty": "Easy",
      "question": "1600 + 1000 = ?",
      "options": { "A": "2500", "B": "2600", "C": "2700", "D": "2800" },
      "correct_answer": "B"
    },
    {
      "id": 16,
      "difficulty": "Easy",
      "question": "4000 + 200 = ?",
      "options": { "A": "4100", "B": "4200", "C": "4300", "D": "4000" },
      "correct_answer": "B"
    },
    {
      "id": 17,
      "difficulty": "Easy",
      "question": "1300 + 2700 = ?",
      "options": { "A": "4000", "B": "3900", "C": "4200", "D": "4100" },
      "correct_answer": "A"
    },
    {
      "id": 18,
      "difficulty": "Easy",
      "question": "1900 + 1900 = ?",
      "options": { "A": "3600", "B": "3700", "C": "3800", "D": "3900" },
      "correct_answer": "C"
    },
    {
      "id": 19,
      "difficulty": "Easy",
      "question": "2400 + 2000 = ?",
      "options": { "A": "4300", "B": "4400", "C": "4500", "D": "4600" },
      "correct_answer": "B"
    },
    {
      "id": 20,
      "difficulty": "Easy",
      "question": "1200 + 2800 = ?",
      "options": { "A": "3800", "B": "3900", "C": "4000", "D": "4100" },
      "correct_answer": "C"
    },

    {
      "id": 21,
      "difficulty": "Medium",
      "question": "2345 + 1200 = ?",
      "options": { "A": "3500", "B": "3545", "C": "3600", "D": "3445" },
      "correct_answer": "B"
    },
    {
      "id": 22,
      "difficulty": "Medium",
      "question": "1456 + 2300 = ?",
      "options": { "A": "3656", "B": "3756", "C": "3800", "D": "3900" },
      "correct_answer": "A"
    },
    {
      "id": 23,
      "difficulty": "Medium",
      "question": "1789 + 1000 = ?",
      "options": { "A": "2689", "B": "2789", "C": "2889", "D": "2589" },
      "correct_answer": "B"
    },
    {
      "id": 24,
      "difficulty": "Medium",
      "question": "3210 + 1200 = ?",
      "options": { "A": "4410", "B": "4510", "C": "4310", "D": "4210" },
      "correct_answer": "A"
    },
    {
      "id": 25,
      "difficulty": "Medium",
      "question": "1678 + 2300 = ?",
      "options": { "A": "3878", "B": "3978", "C": "4078", "D": "4178" },
      "correct_answer": "B"
    },
    {
      "id": 26,
      "difficulty": "Medium",
      "question": "2890 + 2100 = ?",
      "options": { "A": "4890", "B": "4990", "C": "5000", "D": "4980" },
      "correct_answer": "B"
    },
    {
      "id": 27,
      "difficulty": "Medium",
      "question": "4567 + 1300 = ?",
      "options": { "A": "5867", "B": "5767", "C": "5967", "D": "5667" },
      "correct_answer": "A"
    },
    {
      "id": 28,
      "difficulty": "Medium",
      "question": "3678 + 1100 = ?",
      "options": { "A": "4678", "B": "4778", "C": "4578", "D": "4878" },
      "correct_answer": "B"
    },
    {
      "id": 29,
      "difficulty": "Medium",
      "question": "4100 + 2400 = ?",
      "options": { "A": "6600", "B": "6500", "C": "6700", "D": "6400" },
      "correct_answer": "B"
    },
    {
      "id": 30,
      "difficulty": "Medium",
      "question": "1890 + 2800 = ?",
      "options": { "A": "4590", "B": "4690", "C": "4790", "D": "4490" },
      "correct_answer": "B"
    },
    {
      "id": 31,
      "difficulty": "Medium",
      "question": "3050 + 1700 = ?",
      "options": { "A": "4750", "B": "4850", "C": "4950", "D": "4650" },
      "correct_answer": "A"
    },
    {
      "id": 32,
      "difficulty": "Medium",
      "question": "2244 + 3300 = ?",
      "options": { "A": "5544", "B": "5444", "C": "5644", "D": "5744" },
      "correct_answer": "A"
    },
    {
      "id": 33,
      "difficulty": "Medium",
      "question": "1500 + 3890 = ?",
      "options": { "A": "5290", "B": "5390", "C": "5490", "D": "5590" },
      "correct_answer": "B"
    },
    {
      "id": 34,
      "difficulty": "Medium",
      "question": "4000 + 2999 = ?",
      "options": { "A": "6999", "B": "7000", "C": "6899", "D": "7099" },
      "correct_answer": "A"
    },
    {
      "id": 35,
      "difficulty": "Medium",
      "question": "2789 + 4100 = ?",
      "options": { "A": "6789", "B": "6889", "C": "6989", "D": "6689" },
      "correct_answer": "B"
    },
    {
      "id": 36,
      "difficulty": "Medium",
      "question": "3333 + 2222 = ?",
      "options": { "A": "5555", "B": "5550", "C": "5522", "D": "5566" },
      "correct_answer": "A"
    },
    {
      "id": 37,
      "difficulty": "Medium",
      "question": "4180 + 1800 = ?",
      "options": { "A": "5980", "B": "6080", "C": "5880", "D": "6180" },
      "correct_answer": "A"
    },
    {
      "id": 38,
      "difficulty": "Medium",
      "question": "2090 + 3900 = ?",
      "options": { "A": "5990", "B": "5890", "C": "5790", "D": "6090" },
      "correct_answer": "A"
    },
    {
      "id": 39,
      "difficulty": "Medium",
      "question": "2980 + 1980 = ?",
      "options": { "A": "4960", "B": "4970", "C": "4980", "D": "4990" },
      "correct_answer": "A"
    },
    {
      "id": 40,
      "difficulty": "Medium",
      "question": "1234 + 4321 = ?",
      "options": { "A": "5455", "B": "5555", "C": "5655", "D": "5755" },
      "correct_answer": "B"
    },
    {
      "id": 41,
      "difficulty": "Hard",
      "question": "4589 + 3678 = ?",
      "options": { "A": "8267", "B": "8157", "C": "8257", "D": "8167" },
      "correct_answer": "A"
    },
    {
      "id": 42,
      "difficulty": "Hard",
      "question": "5690 + 4310 = ?",
      "options": { "A": "9900", "B": "10000", "C": "10100", "D": "10200" },
      "correct_answer": "B"
    },
    {
      "id": 43,
      "difficulty": "Hard",
      "question": "6789 + 2190 = ?",
      "options": { "A": "8879", "B": "8979", "C": "8899", "D": "8989" },
      "correct_answer": "B"
    },
    {
      "id": 44,
      "difficulty": "Hard",
      "question": "7890 + 1789 = ?",
      "options": { "A": "9579", "B": "9689", "C": "9679", "D": "9669" },
      "correct_answer": "C"
    },
    {
      "id": 45,
      "difficulty": "Hard",
      "question": "4567 + 5433 = ?",
      "options": { "A": "10000", "B": "9999", "C": "9900", "D": "10100" },
      "correct_answer": "A"
    },
    {
      "id": 46,
      "difficulty": "Hard",
      "question": "3999 + 2999 = ?",
      "options": { "A": "6000", "B": "5998", "C": "5988", "D": "6998" },
      "correct_answer": "D"
    },
    {
      "id": 47,
      "difficulty": "Hard",
      "question": "5246 + 3246 = ?",
      "options": { "A": "8492", "B": "8592", "C": "8482", "D": "8582" },
      "correct_answer": "A"
    },
    {
      "id": 48,
      "difficulty": "Hard",
      "question": "6123 + 3123 = ?",
      "options": { "A": "9146", "B": "9246", "C": "9226", "D": "9236" },
      "correct_answer": "B"
    },
    {
      "id": 49,
      "difficulty": "Hard",
      "question": "4875 + 4875 = ?",
      "options": { "A": "9650", "B": "9750", "C": "9850", "D": "9670" },
      "correct_answer": "B"
    },
    {
      "id": 50,
      "difficulty": "Hard",
      "question": "6798 + 1201 = ?",
      "options": { "A": "7999", "B": "8000", "C": "8010", "D": "7900" },
      "correct_answer": "A"
    },
    {
      "id": 51,
      "difficulty": "Hard",
      "question": "7891 + 1098 = ?",
      "options": { "A": "8899", "B": "8989", "C": "8999", "D": "8889" },
      "correct_answer": "B"
    },
    {
      "id": 52,
      "difficulty": "Hard",
      "question": "3489 + 4987 = ?",
      "options": { "A": "8476", "B": "8466", "C": "8486", "D": "8496" },
      "correct_answer": "A"
    },
    {
      "id": 53,
      "difficulty": "Hard",
      "question": "4521 + 5890 = ?",
      "options": { "A": "10421", "B": "10411", "C": "10321", "D": "10511" },
      "correct_answer": "B"
    },
    {
      "id": 54,
      "difficulty": "Hard",
      "question": "5555 + 4445 = ?",
      "options": { "A": "9999", "B": "10000", "C": "10100", "D": "9900" },
      "correct_answer": "B"
    },
    {
      "id": 55,
      "difficulty": "Hard",
      "question": "6789 + 3210 = ?",
      "options": { "A": "9999", "B": "10000", "C": "9879", "D": "9889" },
      "correct_answer": "A"
    },
    {
      "id": 56,
      "difficulty": "Hard",
      "question": "3456 + 6543 = ?",
      "options": { "A": "9999", "B": "10000", "C": "9979", "D": "9879" },
      "correct_answer": "A"
    },
    {
      "id": 57,
      "difficulty": "Hard",
      "question": "1999 + 1999 = ?",
      "options": { "A": "3898", "B": "3998", "C": "3890", "D": "2998" },
      "correct_answer": "B"
    },
    {
      "id": 58,
      "difficulty": "Hard",
      "question": "2300 + 7600 = ?",
      "options": { "A": "9800", "B": "9900", "C": "10000", "D": "9700" },
      "correct_answer": "B"
    },
    {
      "id": 59,
      "difficulty": "Hard",
      "question": "4123 + 5876 = ?",
      "options": { "A": "9999", "B": "10000", "C": "10099", "D": "9899" },
      "correct_answer": "A"
    },
    {
      "id": 60,
      "difficulty": "Hard",
      "question": "3899 + 6100 = ?",
      "options": { "A": "9900", "B": "9999", "C": "10000", "D": "9990" },
      "correct_answer": "B"
    }
  ]
}