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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 42 · 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 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.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?
  3. 3.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  4. 4.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  6. 6.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?
  7. 7.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  8. 8.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  9. 9.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  10. 10.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?
  11. 11.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  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.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?
  14. 14.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  15. 15.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  16. 16.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  17. 17.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?
  18. 18.A leapfrog list starts 1, 4 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): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  20. 20.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  21. 21.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?
  22. 22.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  23. 23.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  24. 24.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  25. 25.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  26. 26.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  27. 27.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?
  28. 28.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?
  29. 29.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?
  30. 30.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?
  31. 31.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  32. 32.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?
  33. 33.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.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?
  35. 35.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?
  36. 36.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  37. 37.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  38. 38.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 814
  2. 847
  3. 451
  4. 1122
  5. 880
  6. 484
  7. 605
  8. 1287
  9. 583
  10. 539
  11. 946
  12. 407
  13. 528
  14. 198
  15. 671
  16. 935
  17. 561
  18. 407
  19. 143
  20. 847
  21. 935
  22. 1089
  23. 1012
  24. 143
  25. 418
  26. 957
  27. 462
  28. 319
  29. 198
  30. 550
  31. 726
  32. 957
  33. 528
  34. 1089
  35. 1001
  36. 561
  37. 803
  38. 649
  39. 561
  40. 924

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