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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 422 · 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. 1.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  2. 2.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  3. 3.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  4. 4.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  5. 5.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  6. 6.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?
  7. 7.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  9. 9.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?
  10. 10.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  11. 11.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?
  12. 12.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  13. 13.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  14. 14.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?
  15. 15.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  16. 16.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  18. 18.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?
  19. 19.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?
  20. 20.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  21. 21.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  22. 22.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  23. 23.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  24. 24.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  26. 26.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  27. 27.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?
  28. 28.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  29. 29.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?
  30. 30.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?
  31. 31.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?
  32. 32.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  33. 33.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  35. 35.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  37. 37.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  38. 38.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?
  39. 39.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  40. 40.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =

Answer key

  1. 968
  2. 550
  3. 308
  4. 946
  5. 528
  6. 770
  7. 671
  8. 528
  9. 429
  10. 649
  11. 253
  12. 561
  13. 198
  14. 198
  15. 847
  16. 528
  17. 627
  18. 418
  19. 781
  20. 1111
  21. 704
  22. 792
  23. 836
  24. 671
  25. 726
  26. 374
  27. 726
  28. 1089
  29. 495
  30. 550
  31. 759
  32. 550
  33. 484
  34. 583
  35. 660
  36. 979
  37. 1199
  38. 517
  39. 583
  40. 594

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