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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 957 · 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): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  3. 3.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?
  4. 4.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  5. 5.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  6. 6.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  7. 7.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?
  8. 8.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  10. 10.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  11. 11.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  13. 13.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?
  14. 14.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?
  15. 15.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?
  16. 16.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  17. 17.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  18. 18.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.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?
  20. 20.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  21. 21.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  22. 22.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?
  23. 23.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  24. 24.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?
  25. 25.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  29. 29.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  30. 30.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  31. 31.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  33. 33.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?
  34. 34.A leapfrog list starts 2, 7 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.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  38. 38.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?
  39. 39.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?
  40. 40.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =

Answer key

  1. 836
  2. 1001
  3. 649
  4. 451
  5. 869
  6. 616
  7. 484
  8. 627
  9. 572
  10. 935
  11. 517
  12. 627
  13. 583
  14. 231
  15. 847
  16. 429
  17. 1023
  18. 968
  19. 506
  20. 715
  21. 693
  22. 418
  23. 1287
  24. 319
  25. 550
  26. 418
  27. 308
  28. 1144
  29. 1177
  30. 495
  31. 726
  32. 803
  33. 616
  34. 726
  35. 319
  36. 1177
  37. 671
  38. 704
  39. 429
  40. 143

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