までもない: no need to go that far
Distinguish judging an action unnecessary for the situation from forbidding it or declaring it impossible.
That degree of action is unnecessary
この程度の計算なら、電卓を使うまでもありません。 means that for a calculation this simple, there is no need to use a calculator. The judgment is that the task does not call for going as far as using that tool.
The sentence does not say a calculator cannot be used. It evaluates whether the action is necessary in the current situation, rather than denying the ability or permission to perform it.
Evaluate an action after its dictionary form
Attach the expression to a dictionary-form verb, as in 尋ねるまでもない or 頼むまでもない. 説明書があるので、尋ねるまでもありません。 means that there is a manual, so there is no need to ask.
言うまでもない can describe something as so obvious that it need not be said. Do not automatically interpret it as an order for someone to be quiet; check whether the context evaluates the content as self-evident.
Compare なくてもいい
電卓を使わなくてもいいです。 means that it is fine not to use a calculator. なくてもいい gives permission not to act or says an action is unnecessary, without necessarily evaluating the task as especially simple.
使うまでもない more explicitly judges that the current situation does not require going as far as using a calculator. By contrast, 使ってはいけない prohibits its use. Replacing lack of necessity with prohibition changes the rule conveyed to the listener.
Does 電卓を使うまでもありません。 prohibit using a calculator?
Show the answer and why
No. It judges that there is no need to go to the trouble of using one. A prohibition uses a separate expression such as 使ってはいけない and is not equivalent to a lack of necessity.