What is the measurement 111.009 mm rounded off to four significant digits?

There are quite a few significant digit rules to remember, and the best way to do it is honestly just to memorize them.

The number 111.009 rounded off to four significant digits is: 111.0.

This is because every 0 after a decimal is considered significant.

10 years is the answer

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer