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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 110 · 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): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 4, 9 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 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.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?
  5. 5.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  6. 6.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  7. 7.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  8. 8.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?
  9. 9.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?
  10. 10.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  13. 13.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  15. 15.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?
  16. 16.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  17. 17.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  18. 18.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  19. 19.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?
  20. 20.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  21. 21.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  22. 22.A leapfrog list starts 7, 1 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): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  24. 24.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?
  25. 25.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  26. 26.A leapfrog list starts 5, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  28. 28.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  29. 29.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?
  30. 30.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?
  31. 31.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  32. 32.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  33. 33.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  34. 34.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.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?
  36. 36.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  37. 37.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  38. 38.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  39. 39.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  40. 40.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =

Answer key

  1. 726
  2. 1012
  3. 495
  4. 671
  5. 506
  6. 572
  7. 1111
  8. 1034
  9. 891
  10. 572
  11. 583
  12. 660
  13. 462
  14. 605
  15. 1001
  16. 1287
  17. 143
  18. 671
  19. 583
  20. 583
  21. 704
  22. 473
  23. 517
  24. 451
  25. 726
  26. 1067
  27. 803
  28. 561
  29. 1122
  30. 693
  31. 231
  32. 869
  33. 847
  34. 528
  35. 319
  36. 418
  37. 286
  38. 594
  39. 649
  40. 957

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