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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 943 · 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): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  3. 3.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  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.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?
  6. 6.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  8. 8.A leapfrog list starts 9, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  10. 10.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  11. 11.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?
  12. 12.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?
  13. 13.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  14. 14.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  15. 15.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  16. 16.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  17. 17.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  18. 18.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  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. 20.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  21. 21.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  22. 22.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  23. 23.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  25. 25.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?
  26. 26.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  27. 27.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?
  28. 28.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?
  29. 29.A leapfrog list starts 9, 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): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  31. 31.A leapfrog list starts 8, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.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?
  33. 33.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  34. 34.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  35. 35.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  38. 38.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?
  39. 39.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  40. 40.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =

Answer key

  1. 737
  2. 671
  3. 1199
  4. 561
  5. 198
  6. 1232
  7. 649
  8. 1111
  9. 627
  10. 902
  11. 1122
  12. 957
  13. 748
  14. 418
  15. 671
  16. 517
  17. 957
  18. 561
  19. 583
  20. 308
  21. 451
  22. 759
  23. 1012
  24. 616
  25. 715
  26. 847
  27. 253
  28. 902
  29. 759
  30. 407
  31. 792
  32. 308
  33. 572
  34. 704
  35. 627
  36. 429
  37. 286
  38. 396
  39. 1001
  40. 198

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