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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 466 · 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): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  2. 2.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?
  3. 3.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?
  4. 4.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  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. 6.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  7. 7.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  8. 8.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?
  9. 9.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  10. 10.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  12. 12.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  13. 13.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  14. 14.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?
  15. 15.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.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?
  17. 17.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  18. 18.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  19. 19.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?
  20. 20.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  21. 21.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?
  22. 22.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  23. 23.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  24. 24.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?
  25. 25.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?
  26. 26.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  28. 28.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?
  29. 29.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  31. 31.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?
  32. 32.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  33. 33.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?
  34. 34.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  35. 35.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?
  36. 36.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  37. 37.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.A leapfrog list starts 5, 9 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 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =

Answer key

  1. 1287
  2. 616
  3. 583
  4. 693
  5. 660
  6. 715
  7. 616
  8. 583
  9. 341
  10. 902
  11. 473
  12. 572
  13. 715
  14. 913
  15. 649
  16. 957
  17. 407
  18. 1001
  19. 649
  20. 671
  21. 957
  22. 891
  23. 143
  24. 517
  25. 836
  26. 660
  27. 869
  28. 1089
  29. 1089
  30. 737
  31. 495
  32. 495
  33. 462
  34. 517
  35. 847
  36. 759
  37. 561
  38. 1067
  39. 495
  40. 594

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