Evaluate $\tfrac{21}{9}$to 3 significant figures

Express the product 0.21 and 0.34 in standard form

A student measures a piece of rope and found that it was 1.26m long. If the actual length of the rope was 1.25m, what was the percentage error in the measurement?

Express 123456 to 3 significant figure

Evaluate $\frac{{{(0.5625)}^{2}}-{{(0.4375)}^{2}}}{0.04}$ correct to 3 significant figures

Evaluate $\frac{0.21\times 0.72\times 0.00054}{0.006\times 1.68\times 0.063}$ correct to four significant figures. 

Evaluate $\frac{{{(0.14)}^{2}}\times (0.275)}{7(0.02)}$ correct to 3 decimal places. 

Evaluate 21.05347 – 1.6324 × 0.43 to 3 decimal places

Evaluate $\frac{2.813\times {{10}^{-3}}\times 1.063}{5.637\times {{10}^{-2}}}$reducing each number to two significant figures and leaving your answer in two significant figures