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
- 1.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
- 2.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
- 3.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
- 4.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
- 5.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
- 6.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 7.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
- 8.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
- 9.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
- 10.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?
- 11.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 12.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?
- 13.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
- 14.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 15.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?
- 16.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?
- 17.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
- 18.A leapfrog list starts 7, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 19.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
- 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?
- 21.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
- 22.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?
- 23.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
- 24.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
- 25.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
- 26.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
- 27.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
- 28.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 29.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?
- 30.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?
- 31.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?
- 32.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
- 33.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
- 34.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
- 35.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
- 36.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
- 37.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?
- 38.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
- 39.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?
- 40.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
Answer key
- 429
- 1232
- 1111
- 517
- 1034
- 341
- 748
- 979
- 231
- 374
- 759
- 583
- 363
- 1023
- 759
- 396
- 616
- 825
- 253
- 847
- 770
- 616
- 814
- 583
- 803
- 308
- 946
- 814
- 616
- 627
- 847
- 319
- 484
- 1144
- 506
- 198
- 913
- 1001
- 363
- 913
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