To me on an example of a logs miner??

We look at the log from the miner:

there is data (example):

"eth_getWork"
"result":
["0x5e5cd5e148bf731617c05cc69f4a990223b642f1d9c545f837b0427ae451166c",
"0x185bb34ccb2fa3c9cf41cb20429e92c96102573d3c8ed27d820dba10b5e2b962",
"0x0112e0be826d694b2e62d01511f12a6061fbaec8bc02357593e70e52ba"]}

eth_submitWork","params":
["0x90cafd1401466c81",
"0x5e5cd5e148bf731617c05cc69f4a990223b642f1d9c545f837b0427ae451166c",
"0x6080c976b37988aff954eab92f284afcfc40f84be17ebb5cc3af39b03fad1c58"]}

put share nonce 90cafd1401466c81
SHARE FOUND - (GPU 2) (DIFF: 6.278G)


how is it calculated: (DIFF: 6.278G)