As a rule, we don't use the passive voice with "let". "Allow" or "permit" is normally used instead: We were allowed to do whatever we wanted. We were permitted to drive the vehicle.

Understanding the Context

Accordi... I think that "Let A be a set, let B be a group, and let C be a number." is the most formal phrasing. Since this is a mathematically formal usage, I think that would be preferred, but I don't think any of the phrases you presented are wrong, and "Let A be a set, B a group, and C a number." is shorter and more succinct. On a separate note, we have a sister site for Math you might consult.

Key Insights

The verb let means “allow”, “permit”, “not prevent or forbid”, “pass, go or come” and it's used with an object and the bare infinitive. Are you going to let me drive or not? Don't let h... Thus you don't need to always change each Let's/Let us with a "replacement" however we will presume you do, so we could replace let us with We want to see x and y. MSFT | Complete Microsoft Corp.

Final Thoughts

stock news by MarketWatch. View real-time stock prices and stock quotes for a full financial overview. Welcome to the March 2026 edition of What's new in Microsoft 365 Copilot! Every month, we highlight new features and enhancements to keep Microsoft 365 admins up to date with Copilot features that help your users be more productive and efficient in the apps they use every day. Let’s take a closer look at what’s new this month: User capabilities: Video recap of meetings in Copilot Chat ...