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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 775 · 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.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  2. 2.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  4. 4.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  5. 5.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  6. 6.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?
  7. 7.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  9. 9.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  10. 10.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  13. 13.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  14. 14.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  15. 15.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  16. 16.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  17. 17.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  18. 18.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?
  19. 19.A leapfrog list starts 7, 2 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): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  21. 21.A leapfrog list starts 2, 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): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  23. 23.A leapfrog list starts 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.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?
  25. 25.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  27. 27.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  28. 28.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  30. 30.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  31. 31.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.A leapfrog list starts 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  35. 35.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  36. 36.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  37. 37.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  38. 38.Leapfrog list (each number is the sum of the two before it): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  39. 39.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?
  40. 40.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =

Answer key

  1. 451
  2. 473
  3. 1056
  4. 1144
  5. 572
  6. 1089
  7. 143
  8. 143
  9. 1034
  10. 1177
  11. 770
  12. 693
  13. 550
  14. 693
  15. 363
  16. 1056
  17. 825
  18. 594
  19. 561
  20. 924
  21. 726
  22. 671
  23. 396
  24. 429
  25. 1232
  26. 968
  27. 627
  28. 935
  29. 583
  30. 407
  31. 253
  32. 605
  33. 748
  34. 847
  35. 1287
  36. 803
  37. 649
  38. 957
  39. 484
  40. 935

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