Update 2.87.md

Fix 0x3BB0

Author: monque

chapter2/2.87.md

@@ -7,4 +7,4 @@
 | 512 | 0x6000 | 1 | 9 | 512 | 512.0 |
 | bigest denormalized | 0x03FF | 1023/1024 | -14 | 1023/(2^24) | 6.09755516e-5 |
 | -oo | 0xFC00 | - | - | -oo | -oo |
-| ox3BB0 | 0x3BB0 | 59/64 | -1 | 59/128 | 0.4609375 |
+| ox3BB0 | 0x3BB0 | 123/64 | -1 | 123/128 | 0.9609375 |