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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 550 · 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): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  2. 2.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?
  3. 3.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  4. 4.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  5. 5.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  6. 6.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  7. 7.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?
  8. 8.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?
  9. 9.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  10. 10.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?
  11. 11.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  12. 12.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  13. 13.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  14. 14.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?
  15. 15.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  16. 16.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  17. 17.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?
  18. 18.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.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?
  20. 20.A leapfrog list starts 4, 5 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): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  22. 22.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  23. 23.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  25. 25.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?
  26. 26.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  27. 27.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  28. 28.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?
  29. 29.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  30. 30.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  31. 31.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  33. 33.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  34. 34.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?
  35. 35.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?
  36. 36.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  37. 37.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  38. 38.A leapfrog list starts 2, 6 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): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  40. 40.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 473
  2. 649
  3. 1111
  4. 616
  5. 627
  6. 814
  7. 660
  8. 484
  9. 803
  10. 583
  11. 979
  12. 495
  13. 341
  14. 671
  15. 319
  16. 649
  17. 429
  18. 759
  19. 473
  20. 660
  21. 803
  22. 1034
  23. 308
  24. 935
  25. 418
  26. 957
  27. 968
  28. 451
  29. 869
  30. 770
  31. 253
  32. 682
  33. 1144
  34. 374
  35. 803
  36. 528
  37. 198
  38. 638
  39. 341
  40. 1199

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