If the questions is referring to the tube, then only one.
Typically, 38-40.
As a chemical weapon (the original purpose) there was no replacement, due to removal of chemical weapons from the inventory. As a mortar, it was replaced by the current 81mm mortar, which has a much longer range than the earlier 81mms. There's also a 120mm smoothbore mortar which replaced some of the 4.2 mortars. It's more commonly found in mechanized units, as it would be quite cumbersome to carry by foot.
81mm is more ie 81mm=8.1cm
81mm
No. WWII mortars could not even destroy WWII tanks. The US had 60mm and 81mm mortars in its frontline units. There were excellent against machine gun nests and troops in foxholes. But the best US mortar was the 4.2 inch "chemical" mortar. The US had about 25 battalions of these, and they were distributed around by companies. This was a much larger weapon than the 81mm mortar, designed to fire white phosphorous and smoke shells - hence the "chemical" designation. But there was also a high-explosive round for the "four deuce" mortar, and the infantry troops loved to have these guys around. But even a 4.2 inch chemical mortar could do little harm to even the tanks of WWII. The best you could hope for would be an extremely lucky hit that would disable one of the tank's treads, maybe cause it to come off. You could never aim and hit a target like that, it would be pure luck.
8.1cm (divide mm by 10 to get cm)
C7 envelopes are 81mm x 114mm.
A 60mm mortar was a super hand grenade with extra long range. Light enough to carry, and with small rounds, plenty of shells could be carried. An 81mm was very heavy to carry...and the rounds were really big and heavy...when carried by hand over long distances.
It differs from 1mm to over 30mm
M16 rifles; 81mm mortar, M48 Patton tanks, M113 APC/ACAV (Armored Personnel Carrier/Armored Cavalry Assault Vehicle), Swift Boats (PCF), UH-1 Huey helicopters, Cobra helicopters, F4 Phantom jets, and B-52 bombers.
If the area is 81 millimeters, the side length is the square root of that, or 9 millimeters.