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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 451 · 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, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  3. 3.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  5. 5.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  6. 6.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  7. 7.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?
  8. 8.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  9. 9.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  11. 11.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  13. 13.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?
  14. 14.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  15. 15.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  16. 16.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?
  17. 17.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  18. 18.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  19. 19.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  21. 21.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?
  22. 22.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?
  23. 23.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?
  24. 24.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  25. 25.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  27. 27.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  28. 28.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?
  29. 29.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?
  30. 30.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?
  31. 31.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?
  32. 32.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?
  33. 33.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  34. 34.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  35. 35.A leapfrog list starts 4, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.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?
  37. 37.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  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 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =

Answer key

  1. 550
  2. 660
  3. 847
  4. 858
  5. 407
  6. 671
  7. 869
  8. 748
  9. 902
  10. 198
  11. 1144
  12. 1001
  13. 616
  14. 308
  15. 880
  16. 1111
  17. 616
  18. 759
  19. 418
  20. 1023
  21. 198
  22. 671
  23. 528
  24. 495
  25. 429
  26. 792
  27. 451
  28. 1122
  29. 847
  30. 1067
  31. 198
  32. 517
  33. 649
  34. 1122
  35. 1012
  36. 319
  37. 473
  38. 671
  39. 473
  40. 847

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