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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 772 · 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, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  2. 2.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?
  3. 3.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  4. 4.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?
  5. 5.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?
  6. 6.A leapfrog list starts 9, 9 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): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  8. 8.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  9. 9.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.A leapfrog list starts 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  13. 13.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  15. 15.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?
  16. 16.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  17. 17.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  18. 18.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  19. 19.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  20. 20.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  21. 21.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  22. 22.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?
  23. 23.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.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?
  25. 25.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?
  26. 26.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?
  27. 27.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  28. 28.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  29. 29.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?
  30. 30.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  31. 31.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?
  32. 32.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  34. 34.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?
  35. 35.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  36. 36.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?
  37. 37.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?
  38. 38.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  39. 39.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  40. 40.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?

Answer key

  1. 638
  2. 616
  3. 319
  4. 396
  5. 1067
  6. 1287
  7. 748
  8. 792
  9. 913
  10. 605
  11. 198
  12. 1012
  13. 1023
  14. 968
  15. 1012
  16. 253
  17. 583
  18. 1056
  19. 627
  20. 1287
  21. 341
  22. 671
  23. 539
  24. 1144
  25. 550
  26. 253
  27. 1232
  28. 759
  29. 1287
  30. 561
  31. 198
  32. 946
  33. 1177
  34. 198
  35. 616
  36. 143
  37. 462
  38. 462
  39. 979
  40. 814

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