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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 950 · 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): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  2. 2.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  3. 3.A leapfrog list starts 6, 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): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  5. 5.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?
  6. 6.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  7. 7.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?
  8. 8.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  9. 9.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  11. 11.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  12. 12.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?
  13. 13.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  14. 14.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  15. 15.A leapfrog list starts 3, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  18. 18.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  19. 19.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  20. 20.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  21. 21.A leapfrog list starts 4, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.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?
  23. 23.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  24. 24.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?
  25. 25.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?
  26. 26.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  28. 28.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  29. 29.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  30. 30.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?
  31. 31.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.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?
  33. 33.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?
  34. 34.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  36. 36.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  37. 37.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?
  38. 38.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  39. 39.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  40. 40.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?

Answer key

  1. 715
  2. 847
  3. 858
  4. 968
  5. 231
  6. 396
  7. 561
  8. 858
  9. 451
  10. 1089
  11. 924
  12. 671
  13. 792
  14. 253
  15. 781
  16. 770
  17. 1056
  18. 671
  19. 429
  20. 748
  21. 1012
  22. 704
  23. 759
  24. 253
  25. 836
  26. 473
  27. 946
  28. 869
  29. 308
  30. 517
  31. 946
  32. 935
  33. 1001
  34. 693
  35. 913
  36. 495
  37. 429
  38. 198
  39. 1001
  40. 1232

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