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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 77 · 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. 1.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  2. 2.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  3. 3.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?
  4. 4.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  5. 5.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  6. 6.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  7. 7.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?
  8. 8.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  9. 9.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  10. 10.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?
  11. 11.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  12. 12.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?
  13. 13.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  14. 14.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  15. 15.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  17. 17.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?
  18. 18.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  19. 19.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  20. 20.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?
  21. 21.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  22. 22.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  23. 23.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  24. 24.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?
  25. 25.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  26. 26.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?
  27. 27.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?
  28. 28.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  29. 29.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?
  30. 30.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?
  31. 31.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  32. 32.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  33. 33.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  35. 35.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  37. 37.A leapfrog list starts 5, 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 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  40. 40.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?

Answer key

  1. 1001
  2. 847
  3. 198
  4. 1177
  5. 1012
  6. 935
  7. 957
  8. 1067
  9. 836
  10. 638
  11. 231
  12. 1023
  13. 583
  14. 913
  15. 253
  16. 671
  17. 583
  18. 891
  19. 924
  20. 253
  21. 418
  22. 231
  23. 253
  24. 913
  25. 858
  26. 561
  27. 407
  28. 374
  29. 429
  30. 462
  31. 396
  32. 847
  33. 759
  34. 1232
  35. 1023
  36. 726
  37. 451
  38. 1001
  39. 143
  40. 539

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