36×56+46×45-38=36×55+36+36×45+10×45-38=36×(55+45)+10×45+36-38=36×100+450-2=3600+450-2=4050-2=4048
=36x56+46x44+46-38=36x56+（36+10）x44+8=36x56+36x44+10x44+8=36x（56+44）+440+8=36x100+448=3600+448=4048
