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This article is from the Fall 1997 AFRMA Rat & Mouse Tales news-magazine.
How fast can mice multiply? Start with 2 baby mice, one of each sex. At 6 weeks old the female can become pregnant. Gestation is 3 weeks, and under optimal conditions the female can become pregnant again immediately after giving birth. Assume a litter of eight, four male and four female, which are paired and bred when they are 6 weeks old. Theoretically you could get:
| Week | Females X | Males = | Babies | Total Mice |
| 3 | 1 | 1 | 0 | 2 |
| 6 | 1 | 1 | 0 | 2 |
| 9 | 1 | 1 | 8 | 10 |
| 12 | 1 | 1 | 8 | 18 |
| 15 | 1 | 1 | 8 | 26 |
| 18 | 5 | 5 | 40 | 66 |
| 21 | 9 | 9 | 72 | 138 |
| 24 | 13 | 13 | 104 | 242 |
| 27 | 33 | 33 | 264 | 506 |
| 30 | 69 | 69 | 552 | 1058 |
| 33 | 121 | 121 | 968 | 2026 |
| 36 | 253 | 253 | 2024 | 4050 |
| 39 | 529 | 529 | 4232 | 8282 |
| 42 | 1013 | 1013 | 8104 | 16386 |
| 45 | 2025 | 2025 | 16200 | 32586 |
| 48 | 4141 | 4141 | 33128 | 65714 |
| 51 | 8193 | 8193 | 65544 | 131258 |
Yes, that’s over one hundred thousand mice in one year!
Caution: don’t try this at home.
Challenge:
How many more weeks will it take before you have over 1 million mice?
See answer here (put mouse over underline):
You will have over a million mice in only 9 more weeks!
