Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 249 · 40 questions

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.

1. 1.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
2. 2.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
3. 3.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
4. 4.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
5. 5.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
6. 6.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
7. 7.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
8. 8.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
9. 9.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
10. 10.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
11. 11.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
12. 12.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
13. 13.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?
14. 14.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?
15. 15.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
16. 16.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?
17. 17.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?
18. 18.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
19. 19.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?
20. 20.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
21. 21.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
22. 22.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
23. 23.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?
24. 24.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
25. 25.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
26. 26.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
27. 27.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
28. 28.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
29. 29.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
30. 30.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?
31. 31.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
32. 32.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
33. 33.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
34. 34.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
35. 35.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
36. 36.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
37. 37.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
38. 38.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
39. 39.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?
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?

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