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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 320 · 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): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  2. 2.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?
  3. 3.A leapfrog list starts 3, 9 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): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  5. 5.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  6. 6.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  7. 7.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  8. 8.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  9. 9.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  10. 10.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  11. 11.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?
  12. 12.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?
  13. 13.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  14. 14.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?
  15. 15.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.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?
  17. 17.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?
  18. 18.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  20. 20.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  21. 21.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  23. 23.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  24. 24.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  26. 26.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  27. 27.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?
  28. 28.A leapfrog list starts 6, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  30. 30.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  31. 31.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?
  32. 32.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  33. 33.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  34. 34.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?
  35. 35.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?
  36. 36.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?
  37. 37.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?
  38. 38.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  40. 40.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =

Answer key

  1. 957
  2. 583
  3. 957
  4. 693
  5. 341
  6. 649
  7. 968
  8. 550
  9. 891
  10. 1034
  11. 495
  12. 407
  13. 924
  14. 671
  15. 1001
  16. 671
  17. 616
  18. 770
  19. 451
  20. 825
  21. 1012
  22. 847
  23. 726
  24. 968
  25. 363
  26. 484
  27. 781
  28. 682
  29. 682
  30. 781
  31. 814
  32. 836
  33. 704
  34. 770
  35. 913
  36. 572
  37. 550
  38. 847
  39. 1122
  40. 1287

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