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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 829 · 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.

NameDateTime takenScore ___ / 40
  1. 1.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  3. 3.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  5. 5.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  6. 6.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  7. 7.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?
  8. 8.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  9. 9.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  10. 10.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  11. 11.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 8, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  14. 14.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  15. 15.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?
  16. 16.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  17. 17.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  18. 18.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  19. 19.A leapfrog list starts 4, 5 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): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  21. 21.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  22. 22.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?
  23. 23.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  24. 24.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  26. 26.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  27. 27.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  28. 28.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  29. 29.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  31. 31.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  32. 32.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  35. 35.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  36. 36.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  38. 38.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?
  39. 39.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?

Answer key

  1. 979
  2. 429
  3. 924
  4. 858
  5. 671
  6. 869
  7. 429
  8. 836
  9. 759
  10. 374
  11. 671
  12. 792
  13. 484
  14. 726
  15. 341
  16. 605
  17. 814
  18. 407
  19. 660
  20. 253
  21. 473
  22. 231
  23. 319
  24. 319
  25. 539
  26. 737
  27. 484
  28. 1287
  29. 1034
  30. 638
  31. 1122
  32. 759
  33. 781
  34. 550
  35. 957
  36. 627
  37. 572
  38. 957
  39. 605
  40. 671

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