1287又二分之一乘以43加430乘以870又4分之1加430
=1287又1/2*43+430*870又1/4+430
=1287.5×43+430×870.25+430
=128.75×430+430×870.25+430
=430×（128.75+870.25+1）
=430×1000
=430000