It's already there.
It is already at the nearest 10, so the answer is 340.
10 of them.
340
350
340
1140
340
340
10.0
340
7.21 is approximate to:10 to the nearest ten7 to the nearest whole number/unit7.2 to the nearest tenth
8.02 is approximate to:10 to the nearest ten8 to the nearest whole number/unit8.0 to the nearest tenth