668.
1)(437×8-(1961+6583):534):145=

2)1000-((715×20+1348):163+879)=

3)484+(18×(345+4465:235)-3400):197

1)1.1961+6583=85442.8544:534=163.437*8=34964.3496-16=34805.3480:145=242)1.715*20=143002.14300+1348=156483.15648:163=964.96+879=9755.1000-976=253)1.4465:235=192.345+19=3643.18*364=65524.6552-3400=31525.3152:197=166.484+16=500