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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 3 · 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.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  4. 4.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  5. 5.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  9. 9.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?
  10. 10.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  11. 11.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?
  12. 12.A leapfrog list starts 7, 5 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): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  14. 14.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  15. 15.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?
  16. 16.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?
  17. 17.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  18. 18.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  20. 20.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  21. 21.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  22. 22.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?
  23. 23.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  24. 24.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?
  25. 25.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?
  26. 26.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  27. 27.A leapfrog list starts 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  29. 29.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  30. 30.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  33. 33.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?
  34. 34.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?
  35. 35.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?
  36. 36.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?
  37. 37.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  38. 38.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?
  39. 39.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.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?

Answer key

  1. 1023
  2. 957
  3. 792
  4. 737
  5. 198
  6. 583
  7. 869
  8. 374
  9. 561
  10. 924
  11. 913
  12. 825
  13. 946
  14. 880
  15. 572
  16. 770
  17. 913
  18. 319
  19. 473
  20. 792
  21. 671
  22. 550
  23. 759
  24. 1034
  25. 198
  26. 539
  27. 374
  28. 583
  29. 847
  30. 847
  31. 341
  32. 594
  33. 253
  34. 847
  35. 671
  36. 286
  37. 451
  38. 693
  39. 891
  40. 583

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