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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 676 · 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): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.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?
  4. 4.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.A leapfrog list starts 5, 5 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 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.A leapfrog list starts 2, 4 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): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  9. 9.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?
  10. 10.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  11. 11.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  12. 12.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  13. 13.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  14. 14.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  15. 15.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  16. 16.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  17. 17.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  18. 18.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?
  19. 19.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  20. 20.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?
  21. 21.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?
  22. 22.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  23. 23.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?
  24. 24.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  25. 25.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  26. 26.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?
  27. 27.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  28. 28.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  29. 29.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  30. 30.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  32. 32.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?
  33. 33.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  34. 34.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  35. 35.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  36. 36.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  37. 37.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  38. 38.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?
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?

Answer key

  1. 374
  2. 539
  3. 583
  4. 429
  5. 715
  6. 891
  7. 462
  8. 638
  9. 770
  10. 649
  11. 418
  12. 781
  13. 737
  14. 693
  15. 506
  16. 891
  17. 957
  18. 550
  19. 1067
  20. 726
  21. 528
  22. 979
  23. 1122
  24. 583
  25. 616
  26. 517
  27. 550
  28. 374
  29. 803
  30. 517
  31. 418
  32. 968
  33. 1023
  34. 1023
  35. 143
  36. 1232
  37. 286
  38. 671
  39. 583
  40. 462

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