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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 435 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

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  1. 1.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  4. 4.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  6. 6.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  7. 7.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  9. 9.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.A leapfrog list starts 9, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  12. 12.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  13. 13.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  14. 14.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  15. 15.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  16. 16.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  17. 17.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  18. 18.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  19. 19.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  21. 21.A leapfrog list starts 1, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  23. 23.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  26. 26.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  27. 27.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  29. 29.A leapfrog list starts 6, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  32. 32.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  33. 33.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  37. 37.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  38. 38.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?

Answer key

  1. 957
  2. 781
  3. 836
  4. 924
  5. 902
  6. 583
  7. 517
  8. 616
  9. 528
  10. 1287
  11. 198
  12. 308
  13. 1067
  14. 693
  15. 880
  16. 759
  17. 363
  18. 418
  19. 462
  20. 495
  21. 671
  22. 924
  23. 308
  24. 506
  25. 429
  26. 561
  27. 1199
  28. 1023
  29. 682
  30. 748
  31. 341
  32. 1089
  33. 594
  34. 473
  35. 341
  36. 1067
  37. 506
  38. 231
  39. 913
  40. 550

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