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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 982 · 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, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  2. 2.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  3. 3.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  4. 4.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  6. 6.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  7. 7.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  8. 8.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  9. 9.A leapfrog list starts 3, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  11. 11.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?
  12. 12.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?
  13. 13.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  14. 14.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  15. 15.A leapfrog list starts 8, 7 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 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  18. 18.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?
  19. 19.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  20. 20.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?
  21. 21.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?
  22. 22.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?
  23. 23.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  24. 24.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?
  25. 25.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  26. 26.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  29. 29.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?
  30. 30.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  31. 31.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  32. 32.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?
  33. 33.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  34. 34.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?
  35. 35.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?
  36. 36.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  37. 37.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?
  38. 38.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  39. 39.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  40. 40.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?

Answer key

  1. 407
  2. 1001
  3. 473
  4. 770
  5. 979
  6. 726
  7. 231
  8. 594
  9. 869
  10. 858
  11. 792
  12. 253
  13. 286
  14. 1012
  15. 1056
  16. 374
  17. 704
  18. 451
  19. 429
  20. 847
  21. 451
  22. 1067
  23. 814
  24. 550
  25. 759
  26. 583
  27. 583
  28. 374
  29. 979
  30. 451
  31. 715
  32. 1287
  33. 1023
  34. 616
  35. 1144
  36. 880
  37. 671
  38. 1067
  39. 660
  40. 539

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