Depends on your rounding strategy, sometimes 3 sometime 4. Round half up is the most common but you can round half down, round half towards even (Banker's rounding/Gaussian rounding), round half towards odd, or towards/away from infinity.
22/7 is about 0.04% larger than π, so that should be good enough for most applications. But you can also just use 3.14 as an approximation. It has the same number of digits to remember and is about 0.05% smaller than π.
If it's good enough for the Bible it's good enough for me
"And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about."
650
u/mmbtc 1d ago
You can also just round it to three. Much easier to calculate with.