Leapfrog Sum Trick Worksheet
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
- 1.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
- 2.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
- 3.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?
- 4.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
- 5.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 6.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
- 7.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?
- 8.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
- 9.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
- 10.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
- 11.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
- 12.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
- 13.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
- 14.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 15.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
- 16.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?
- 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?
- 18.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
- 19.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?
- 20.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
- 21.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
- 22.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?
- 23.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
- 24.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 25.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
- 26.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?
- 27.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?
- 28.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
- 29.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?
- 30.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
- 31.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 32.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?
- 33.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?
- 34.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?
- 35.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?
- 36.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?
- 37.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?
- 38.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
- 39.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
- 40.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
Answer key
- 583
- 561
- 748
- 451
- 418
- 506
- 429
- 759
- 1199
- 979
- 770
- 231
- 902
- 286
- 1287
- 891
- 253
- 594
- 847
- 1177
- 660
- 198
- 616
- 1001
- 715
- 1067
- 583
- 880
- 616
- 363
- 693
- 759
- 341
- 1287
- 451
- 572
- 462
- 550
- 506
- 407
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