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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 212 · 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. 1.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  2. 2.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  3. 3.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?
  4. 4.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  5. 5.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  6. 6.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?
  7. 7.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?
  8. 8.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  9. 9.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?
  10. 10.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  11. 11.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?
  12. 12.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?
  13. 13.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  14. 14.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  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. 16.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  17. 17.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  18. 18.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  19. 19.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  21. 21.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?
  22. 22.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  23. 23.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  24. 24.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?
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  27. 27.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  28. 28.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  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.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?
  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. 32.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  33. 33.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  34. 34.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?
  35. 35.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.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?
  37. 37.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  38. 38.A leapfrog list starts 7, 2 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): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  40. 40.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =

Answer key

  1. 572
  2. 1199
  3. 1144
  4. 583
  5. 341
  6. 759
  7. 319
  8. 1067
  9. 1067
  10. 627
  11. 638
  12. 429
  13. 825
  14. 803
  15. 869
  16. 473
  17. 143
  18. 605
  19. 924
  20. 253
  21. 506
  22. 935
  23. 396
  24. 451
  25. 913
  26. 407
  27. 671
  28. 286
  29. 616
  30. 627
  31. 583
  32. 737
  33. 363
  34. 880
  35. 1232
  36. 495
  37. 913
  38. 561
  39. 286
  40. 594

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