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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 120 · 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, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  2. 2.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  4. 4.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  5. 5.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?
  6. 6.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  7. 7.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?
  8. 8.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  9. 9.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?
  10. 10.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  11. 11.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?
  12. 12.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?
  13. 13.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?
  14. 14.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?
  15. 15.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?
  16. 16.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?
  17. 17.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  18. 18.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  19. 19.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  21. 21.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  22. 22.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  23. 23.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  24. 24.Leapfrog list (each number is the sum of the two before it): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  25. 25.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?
  26. 26.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?
  27. 27.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  28. 28.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  30. 30.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  31. 31.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  32. 32.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?
  33. 33.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  35. 35.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?
  36. 36.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  38. 38.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?
  39. 39.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  40. 40.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?

Answer key

  1. 550
  2. 704
  3. 979
  4. 308
  5. 429
  6. 462
  7. 704
  8. 638
  9. 286
  10. 594
  11. 924
  12. 913
  13. 506
  14. 451
  15. 682
  16. 671
  17. 660
  18. 363
  19. 924
  20. 473
  21. 605
  22. 869
  23. 1023
  24. 957
  25. 407
  26. 1287
  27. 539
  28. 957
  29. 1232
  30. 1111
  31. 429
  32. 649
  33. 924
  34. 1067
  35. 616
  36. 231
  37. 143
  38. 1111
  39. 451
  40. 671

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