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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 644 · 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): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  3. 3.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?
  4. 4.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?
  5. 5.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  6. 6.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  7. 7.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  9. 9.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  10. 10.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?
  11. 11.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  12. 12.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?
  13. 13.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  15. 15.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  16. 16.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?
  17. 17.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  18. 18.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  19. 19.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  20. 20.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  21. 21.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  22. 22.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  23. 23.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?
  24. 24.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.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?
  27. 27.A leapfrog list starts 8, 8 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 7, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  30. 30.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  31. 31.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?
  32. 32.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?
  33. 33.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  35. 35.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  36. 36.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?
  37. 37.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?
  38. 38.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  39. 39.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?

Answer key

  1. 616
  2. 748
  3. 671
  4. 341
  5. 616
  6. 869
  7. 770
  8. 649
  9. 374
  10. 891
  11. 924
  12. 374
  13. 561
  14. 704
  15. 143
  16. 924
  17. 891
  18. 649
  19. 418
  20. 1144
  21. 913
  22. 968
  23. 198
  24. 638
  25. 715
  26. 770
  27. 1144
  28. 825
  29. 550
  30. 1067
  31. 814
  32. 902
  33. 583
  34. 902
  35. 627
  36. 671
  37. 506
  38. 539
  39. 836
  40. 561

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