The sum of $3 + 7 + 90$ is:

$3 + 7 + 90 = 100$

Do you want details or have any questions?

Here are 5 questions you might want to ask next:

1. How do I solve a quadratic equation?
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4. Can you explain the Pythagorean theorem?
5. How do you simplify algebraic expressions?

Tip: When adding multiple numbers, it's often helpful to group them into smaller, more manageable sums.