Easy way to know... /levelup, then /getexp 200000, then divide 200000 by the number of Exp in bars (e.g. 524%) you got, *1000. There you have your number of exp :)
But to make you easy, here's a list:
Read $level['x'] = y as: You need Y exp to levelup from level X-1 to level X
PHP Code:
$level['2'] = 5;
$level['3'] = 24;
$level['4'] = 60;
$level['5'] = 160;
$level['6'] = 328;
$level['7'] = 548;
$level['8'] = 814;
$level['9'] = 1157;
$level['10'] = 1558;
$level['11'] = 2250;
$level['12'] = 3086;
$level['13'] = 4135;
$level['14'] = 5444;
$level['15'] = 7068;
$level['16'] = 9126;
$level['17'] = 11660;
$level['18'] = 14769;
$level['19'] = 18572;
$level['20'] = 23214;
$level['21'] = 29155;
$level['22'] = 36409;
$level['23'] = 45245;
$level['24'] = 55988;
$level['25'] = 69026;
$level['26'] = 85569;
$level['27'] = 105656;
$level['28'] = 130009;
$level['29'] = 159494;
$level['30'] = 159150;
$level['31'] = 238255;
$level['32'] = 290216;
$level['33'] = 352918;
$level['34'] = 428488;
$level['35'] = 519513;
$level['36'] = 629149;
$level['37'] = 761081;
$level['38'] = 919784;
$level['39'] = 1110624;
$level['40'] = 1340045;
$level['41'] = 1615778;
$level['42'] = 1947099;
$level['43'] = 2345141;
$level['44'] = 2823265;
$level['45'] = 3397501;
$level['46'] = 4087087;
$level['47'] = 4915108;
$level['48'] = 5909267;
$level['49'] = 7102808;
$level['50'] = 8535623;
$level['51'] = 10255633;
$level['52'] = 12320243;
$level['53'] = 14798389;
$level['54'] = 17772795;
$level['55'] = 21342730;
$level['56'] = 25627317;
$level['57'] = 30769501;
$level['58'] = 36940820;
$level['59'] = 44347118;
$level['60'] = 53235407;
$level['61'] = 63902104;
$level['62'] = 76702906;
$level['63'] = 92064653;
$level['64'] = 110499551;
$level['65'] = 132622249;
$level['66'] = 169170373;
$level['67'] = 191028978;
$level['68'] = 229260177;
$level['69'] = 275138508;
$level['70'] = 330193415;
$level['71'] = 396260232;
$level['72'] = 1188853398;
$level['73'] = 1426699190;
$level['74'] = 1712116603;
$level['75'] = 2054620005;
$level['76'] = 2465627972;
$level['77'] = 2958842501;
$level['78'] = 3550695049;
$level['79'] = 4260939963;
$level['80'] = 5113193317;
$level['81'] = 6135910416;
$level['82'] = 7363228039;
$level['83'] = 8835873647;
$level['84'] = 10603329445;
$level['85'] = 12723860419;
$level['86'] = 15268923922;
$level['87'] = 18322568824;
$level['88'] = 21987686895;
$level['89'] = 26385224274;
$level['90'] = 31663104567;
$level['91'] = 37993920972;
$level['92'] = 45594437478;
$level['93'] = 54712077691;
$level['94'] = 65659881812;
$level['95'] = 78786685050;
$level['96'] = 94540297802;
$level['97'] = 113442994895;
$level['98'] = 136147038801;
$level['99'] = 163398692810;