[750² + 150000 + √1452025]

seven-hundred-fifty squared, plus one-million-five-hundred-thousand, plus the square root of one-million-four-hundred-fifty-two-thousand-and-twenty-five

(3.4 × 10^-4) + [(191÷ 382)²] + (1.5 ÷ 25)

three-point-four times ten to the minus four, plus one-hundred-ninety-one divided by three-hundred-eighty-two all squared, plus one-point-fve divided by twent-five.

There are many ways to say these, and English is not always precise (for example in saying what exactly gets squared just above), so that is why we use formulas!

The "[" is an "open square bracket"
The "]" is a "close square bracket"