WORKSHEETName : ..Class : ..No. : ..MENTAL MATHEMATICSThereareseveral techniques for doingcalculationmentally. Wewilldiscuss four of them:Properties,CompatibleNumbers,Compensation,and Left to Right Methods. 1. PropertiesExample:. Calculating 25+(38+35)25+( 38+35)=( .+35)+25+(35+)+60!use properties"2. Calculating #$ .1914. 3232 19 14 32=3219... 14KeywordCalculatin ! "en#itun Co"pati$le ! serasiCo"pensation ! penantian %i&&erences ! selisi#Hundreds ! ratusan Le&t to ri#t ! 'iri 'e 'ananOnes ! satuan Su"s ! (u"la#Tens ! pulu#an )uantities ! #asil $aiRe&or"ulatin ! "enyusun ulan Products ! #asil 'aliCommutativea+b=b+aorab=ba%ssociativea+(b+c)=(a+b)+cora(bc)=(ab)c &istri'utivea(b+c)=ab+acorab+ac=a(b+c)32(...)32 !use properties"Calculating mentally using properties(a.(64+35)+26=......b.14. 7+14. 23= ..2. Co"pati$le Nu"$ersCompati'le num'ers are num'ers whose sums) differences) products) orquantities are easy to calculate.Example:** and $# are compati'le num'ers under ...........................+ and $, are compati'le num'ers under .-.. and +. are compati'le num'ers under .Calculatingthefollowingmentallyusingpropertiesand/orcompati'lenum'ers(a.( 817) 25='.7625=..3. Co"pensationThe process of reformulating a sum) differences) product) or quantities toone that is more easily o'tained mentally is compensation.Example: a.26+( 33+18)=( 26+...) +... 0 1. 2 0 '.6728=300Calculating mentally use compensation(a.(23+19)+36= '.25.66=c.5319=...4. Le&t to Ri#t Met#odsExample:. Calculating 456+332%dd the hundreds20.%dd the tens20..%dd the ones 20.. 2 2. Calculate 32364undreds3 0 Tens 9 .0 5nes 9.. 0 2 .Calculating mentally use left to right method(a.246+864= ..'.88. 67=c.765239=. Good luck, god bless mathematician