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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 319 · 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): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  2. 2.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  3. 3.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  4. 4.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  5. 5.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?
  6. 6.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?
  7. 7.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  8. 8.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.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?
  10. 10.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?
  11. 11.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?
  12. 12.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?
  13. 13.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  14. 14.Leapfrog list (each number is the sum of the two before it): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  15. 15.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  17. 17.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?
  18. 18.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.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?
  20. 20.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  21. 21.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  22. 22.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  23. 23.A leapfrog list starts 4, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  25. 25.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  26. 26.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  28. 28.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?
  29. 29.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  30. 30.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?
  31. 31.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?
  32. 32.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  33. 33.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  34. 34.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?
  35. 35.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?
  36. 36.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  38. 38.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  39. 39.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?

Answer key

  1. 1001
  2. 462
  3. 286
  4. 858
  5. 583
  6. 935
  7. 814
  8. 1034
  9. 968
  10. 561
  11. 616
  12. 572
  13. 572
  14. 891
  15. 825
  16. 484
  17. 957
  18. 924
  19. 1089
  20. 957
  21. 561
  22. 748
  23. 836
  24. 814
  25. 968
  26. 583
  27. 341
  28. 946
  29. 1067
  30. 759
  31. 286
  32. 803
  33. 1144
  34. 253
  35. 671
  36. 396
  37. 286
  38. 539
  39. 1199
  40. 451

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