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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 642 · 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): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  2. 2.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?
  3. 3.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  4. 4.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?
  5. 5.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  6. 6.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  7. 7.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  8. 8.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  10. 10.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  11. 11.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  12. 12.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?
  13. 13.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?
  14. 14.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  16. 16.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  18. 18.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  19. 19.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.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?
  21. 21.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  23. 23.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?
  24. 24.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  25. 25.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?
  26. 26.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  27. 27.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  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 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  31. 31.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?
  32. 32.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  33. 33.A leapfrog list starts 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  35. 35.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  36. 36.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?
  37. 37.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  38. 38.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?
  39. 39.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  40. 40.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =

Answer key

  1. 418
  2. 462
  3. 946
  4. 561
  5. 682
  6. 451
  7. 979
  8. 671
  9. 957
  10. 627
  11. 671
  12. 836
  13. 583
  14. 913
  15. 1023
  16. 704
  17. 1056
  18. 1111
  19. 583
  20. 671
  21. 1199
  22. 396
  23. 1144
  24. 1089
  25. 594
  26. 1144
  27. 407
  28. 1089
  29. 308
  30. 726
  31. 1034
  32. 869
  33. 858
  34. 1199
  35. 528
  36. 715
  37. 825
  38. 198
  39. 583
  40. 660

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