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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 463 · 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. 1.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  2. 2.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?
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  4. 4.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  5. 5.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  6. 6.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?
  7. 7.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  8. 8.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?
  9. 9.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  10. 10.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?
  11. 11.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 7, 5 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 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  15. 15.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  16. 16.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  17. 17.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?
  18. 18.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  19. 19.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  20. 20.A leapfrog list starts 1, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  22. 22.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  23. 23.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  25. 25.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  26. 26.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?
  27. 27.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?
  28. 28.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  29. 29.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  32. 32.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  33. 33.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  34. 34.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  35. 35.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  36. 36.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.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?
  38. 38.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?
  39. 39.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?

Answer key

  1. 627
  2. 1067
  3. 836
  4. 143
  5. 726
  6. 583
  7. 341
  8. 451
  9. 1089
  10. 517
  11. 759
  12. 825
  13. 594
  14. 781
  15. 957
  16. 418
  17. 253
  18. 1023
  19. 594
  20. 143
  21. 869
  22. 1287
  23. 726
  24. 1287
  25. 968
  26. 286
  27. 594
  28. 891
  29. 462
  30. 198
  31. 913
  32. 946
  33. 506
  34. 671
  35. 583
  36. 979
  37. 198
  38. 627
  39. 847
  40. 693

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