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
- 1.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
- 2.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?
- 3.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 4.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
- 5.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
- 6.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
- 7.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
- 8.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
- 9.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
- 10.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 11.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
- 12.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?
- 13.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
- 14.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
- 15.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?
- 16.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
- 17.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
- 18.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?
- 19.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?
- 20.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?
- 21.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
- 22.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?
- 23.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
- 24.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 25.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 26.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
- 27.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?
- 28.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
- 29.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
- 30.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?
- 31.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?
- 32.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?
- 33.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?
- 34.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
- 35.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
- 36.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
- 37.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?
- 38.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
- 39.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
- 40.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
Answer key
- 737
- 902
- 649
- 891
- 1001
- 407
- 726
- 671
- 396
- 407
- 1056
- 660
- 836
- 781
- 693
- 759
- 616
- 1012
- 770
- 946
- 792
- 825
- 286
- 594
- 979
- 341
- 638
- 792
- 1023
- 913
- 880
- 583
- 231
- 814
- 539
- 1001
- 1067
- 913
- 253
- 572
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