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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 838 · 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. 1.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  2. 2.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  3. 3.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?
  4. 4.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?
  5. 5.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  6. 6.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  7. 7.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  8. 8.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  9. 9.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  11. 11.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?
  12. 12.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?
  13. 13.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?
  14. 14.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  15. 15.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  16. 16.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  17. 17.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  18. 18.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  19. 19.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?
  20. 20.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.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?
  22. 22.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  23. 23.Leapfrog list (each number is the sum of the two before it): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  24. 24.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  26. 26.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  28. 28.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  29. 29.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.Leapfrog list (each number is the sum of the two before it): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  31. 31.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?
  32. 32.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  33. 33.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  34. 34.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  35. 35.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  36. 36.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  38. 38.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?
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?

Answer key

  1. 363
  2. 781
  3. 231
  4. 671
  5. 616
  6. 770
  7. 583
  8. 253
  9. 1122
  10. 341
  11. 1287
  12. 671
  13. 957
  14. 935
  15. 374
  16. 539
  17. 671
  18. 1111
  19. 638
  20. 341
  21. 726
  22. 550
  23. 517
  24. 286
  25. 660
  26. 572
  27. 638
  28. 924
  29. 704
  30. 748
  31. 715
  32. 594
  33. 858
  34. 704
  35. 396
  36. 913
  37. 693
  38. 253
  39. 913
  40. 913

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