A data read start decision device includes: a storing circuit configured to store code key data; a read check circuit configured to output a read start signal in response to code key data read from the storing circuit, and a controller configured to start reading environment setting data from the storing circuit in response to the read start signal. For example, various tools used to level items andor as a straight edge for aligning or drawing lines on items may be designed in an improved or augmented I beam style so that they are lightweight, strong, durable and rigid so as to hold their shape under stress or return to their original shape after being stressed. A carry-lookahead adder receives the outputs from the carry-save adder and implements an XOR operation on a most-significant bit along with its own logic operation to produce a value for the floating point multiply-accumulate operation.