fix Big number issue in the guide

[codomposer]

Fix BigDecimal precision issues

Problem

Using new BigDecimal(double) causes precision issues:

new BigDecimal(0.1) // 0.1000000000000000055511151231257827021181583404541015625

Solution

Replace with BigDecimal.valueOf(double)

BigDecimal.valueOf(0.1) // 0.1

Fixes

Closes #2680 #608 #178

[Snailclimb]

Fix BigDecimal precision issues

Problem

Using new BigDecimal(double) causes precision issues:

new BigDecimal(0.1) // 0.1000000000000000055511151231257827021181583404541015625

Solution

Replace with BigDecimal.valueOf(double)

BigDecimal.valueOf(0.1) // 0.1

Fixes

Closes #2680

感谢修正完善👍