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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 714 · 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, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  2. 2.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?
  3. 3.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  4. 4.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  6. 6.A leapfrog list starts 4, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  8. 8.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?
  9. 9.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  10. 10.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  11. 11.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  12. 12.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.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?
  14. 14.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  15. 15.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?
  16. 16.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  17. 17.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  18. 18.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?
  19. 19.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  20. 20.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?
  21. 21.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  22. 22.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?
  23. 23.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?
  24. 24.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  27. 27.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?
  28. 28.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?
  29. 29.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  31. 31.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?
  32. 32.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?
  33. 33.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?
  34. 34.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  35. 35.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  36. 36.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  38. 38.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?

Answer key

  1. 638
  2. 825
  3. 374
  4. 858
  5. 462
  6. 836
  7. 1001
  8. 660
  9. 847
  10. 968
  11. 539
  12. 418
  13. 583
  14. 583
  15. 528
  16. 781
  17. 528
  18. 341
  19. 1287
  20. 583
  21. 880
  22. 528
  23. 484
  24. 429
  25. 561
  26. 792
  27. 308
  28. 902
  29. 649
  30. 759
  31. 847
  32. 594
  33. 583
  34. 792
  35. 880
  36. 671
  37. 1012
  38. 649
  39. 1111
  40. 308

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