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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 257 · 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. 1.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  2. 2.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?
  3. 3.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  5. 5.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?
  6. 6.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?
  7. 7.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  8. 8.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  9. 9.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?
  10. 10.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  11. 11.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?
  12. 12.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  13. 13.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  14. 14.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  15. 15.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?
  16. 16.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  18. 18.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  20. 20.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  21. 21.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?
  22. 22.A leapfrog list starts 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  24. 24.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  26. 26.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  27. 27.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  28. 28.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?
  29. 29.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  30. 30.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?
  31. 31.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  32. 32.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?
  33. 33.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?
  34. 34.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  35. 35.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.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?
  37. 37.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  39. 39.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  40. 40.A leapfrog list starts 7, 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. 913
  2. 704
  3. 583
  4. 506
  5. 660
  6. 583
  7. 891
  8. 451
  9. 1089
  10. 1111
  11. 968
  12. 1001
  13. 495
  14. 231
  15. 726
  16. 231
  17. 253
  18. 814
  19. 649
  20. 1056
  21. 979
  22. 484
  23. 572
  24. 308
  25. 1089
  26. 946
  27. 902
  28. 1199
  29. 759
  30. 770
  31. 803
  32. 528
  33. 495
  34. 1177
  35. 1144
  36. 759
  37. 616
  38. 682
  39. 671
  40. 1177

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