It is 999.
The largest prime number less than 1000 is 997.The largest prime number no less than 1000 is currently 257,885,161-1
990
1000 ÷ 8 = 125 → largest less than 1000 divisible by 8 is 124 x 8 = 992
Start with 1000 and work back, rejecting any composites that you find.
9797 is the largest prime number less than 100.
67 will be the largest prime number less than 70.
312 = 961
10 less than 1000 = 1000 minus 10 = 990
It is 43876 - 1000 = 42876.
46503 - 1000 = 45503
9385-1000=8385
1000-3=997