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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 111 · 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, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  2. 2.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?
  3. 3.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.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?
  5. 5.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  6. 6.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?
  7. 7.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  8. 8.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  9. 9.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  10. 10.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  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.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  14. 14.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  15. 15.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  16. 16.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  17. 17.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  18. 18.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  19. 19.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  20. 20.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  21. 21.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?
  22. 22.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  23. 23.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?
  24. 24.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.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?
  26. 26.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?
  27. 27.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  28. 28.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  29. 29.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  30. 30.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?
  31. 31.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  32. 32.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?
  33. 33.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  34. 34.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?
  35. 35.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?
  36. 36.A leapfrog list starts 1, 3 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 9, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  39. 39.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?

Answer key

  1. 726
  2. 759
  3. 891
  4. 858
  5. 880
  6. 770
  7. 858
  8. 1023
  9. 253
  10. 847
  11. 1232
  12. 253
  13. 847
  14. 484
  15. 847
  16. 143
  17. 836
  18. 660
  19. 627
  20. 671
  21. 1144
  22. 396
  23. 583
  24. 429
  25. 759
  26. 847
  27. 825
  28. 704
  29. 1144
  30. 1012
  31. 550
  32. 671
  33. 1056
  34. 1232
  35. 627
  36. 319
  37. 1287
  38. 583
  39. 869
  40. 704

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