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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 740 · 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): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  2. 2.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  3. 3.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.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?
  5. 5.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?
  6. 6.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  7. 7.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?
  8. 8.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  9. 9.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?
  10. 10.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  11. 11.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  12. 12.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  13. 13.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
  15. 15.A leapfrog list starts 3, 8 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, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  17. 17.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  18. 18.A leapfrog list starts 2, 9 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, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  20. 20.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  21. 21.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?
  22. 22.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  23. 23.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  24. 24.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?
  25. 25.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.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?
  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): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  30. 30.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  32. 32.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  33. 33.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  34. 34.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?
  35. 35.A leapfrog list starts 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  37. 37.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  40. 40.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?

Answer key

  1. 671
  2. 539
  3. 803
  4. 1177
  5. 1144
  6. 726
  7. 506
  8. 682
  9. 319
  10. 704
  11. 341
  12. 528
  13. 627
  14. 770
  15. 869
  16. 1023
  17. 308
  18. 902
  19. 858
  20. 473
  21. 495
  22. 319
  23. 429
  24. 1001
  25. 715
  26. 759
  27. 550
  28. 968
  29. 616
  30. 495
  31. 583
  32. 1067
  33. 550
  34. 231
  35. 484
  36. 858
  37. 814
  38. 198
  39. 374
  40. 418

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