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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 680 · 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. 1.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  2. 2.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?
  3. 3.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  5. 5.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  8. 8.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  10. 10.A leapfrog list starts 9, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  12. 12.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?
  13. 13.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?
  14. 14.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  15. 15.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  17. 17.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  18. 18.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  19. 19.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.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?
  21. 21.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  22. 22.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  23. 23.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?
  24. 24.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  26. 26.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?
  27. 27.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  28. 28.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?
  29. 29.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?
  30. 30.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  31. 31.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  33. 33.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  34. 34.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  35. 35.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  36. 36.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  37. 37.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?
  38. 38.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 374
  2. 341
  3. 1001
  4. 451
  5. 913
  6. 880
  7. 1023
  8. 506
  9. 418
  10. 1111
  11. 869
  12. 1122
  13. 902
  14. 198
  15. 319
  16. 341
  17. 616
  18. 231
  19. 407
  20. 704
  21. 1067
  22. 253
  23. 561
  24. 143
  25. 407
  26. 935
  27. 671
  28. 968
  29. 429
  30. 396
  31. 847
  32. 1111
  33. 1122
  34. 682
  35. 924
  36. 638
  37. 253
  38. 1232
  39. 451
  40. 847

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