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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 664 · 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): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  2. 2.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?
  3. 3.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  4. 4.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  5. 5.A leapfrog list starts 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  7. 7.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  8. 8.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  9. 9.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.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?
  11. 11.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  13. 13.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  15. 15.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  16. 16.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  18. 18.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  19. 19.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  20. 20.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  22. 22.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?
  23. 23.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  24. 24.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  25. 25.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.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?
  27. 27.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?
  28. 28.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.A leapfrog list starts 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  31. 31.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  33. 33.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?
  34. 34.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  36. 36.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?
  37. 37.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?
  38. 38.A leapfrog list starts 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
  40. 40.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =

Answer key

  1. 759
  2. 396
  3. 913
  4. 286
  5. 484
  6. 638
  7. 1122
  8. 528
  9. 814
  10. 902
  11. 891
  12. 715
  13. 1199
  14. 627
  15. 649
  16. 539
  17. 770
  18. 946
  19. 1287
  20. 583
  21. 231
  22. 682
  23. 583
  24. 1177
  25. 704
  26. 1089
  27. 1177
  28. 1122
  29. 858
  30. 605
  31. 198
  32. 737
  33. 308
  34. 1023
  35. 1023
  36. 693
  37. 935
  38. 374
  39. 770
  40. 759

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