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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 778 · 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): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.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?
  4. 4.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  6. 6.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?
  7. 7.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  8. 8.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  9. 9.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  10. 10.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  11. 11.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?
  12. 12.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  13. 13.A leapfrog list starts 5, 5 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 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.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?
  17. 17.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  18. 18.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  19. 19.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?
  20. 20.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  21. 21.A leapfrog list starts 2, 3 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): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  23. 23.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  24. 24.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  27. 27.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  28. 28.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  29. 29.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  30. 30.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  31. 31.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  33. 33.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  34. 34.A leapfrog list starts 4, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  36. 36.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  37. 37.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?
  38. 38.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 671
  2. 693
  3. 737
  4. 341
  5. 396
  6. 407
  7. 550
  8. 803
  9. 957
  10. 231
  11. 550
  12. 869
  13. 715
  14. 484
  15. 880
  16. 924
  17. 1001
  18. 253
  19. 528
  20. 1232
  21. 374
  22. 891
  23. 924
  24. 143
  25. 583
  26. 1067
  27. 308
  28. 891
  29. 528
  30. 374
  31. 946
  32. 539
  33. 671
  34. 660
  35. 1122
  36. 407
  37. 1111
  38. 462
  39. 858
  40. 704

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