n. 25B6; noun
they ran into a problem : DIFFICULTY, trouble, worry, complication, difficult situation; snag, hitch, drawback, stumbling block, obstacle, hurdle, hiccup, setback, catch; predicament, plight; misfortune, mishap, misadventure; informal dilemma, headache, prob, facer.
I don't want to be a problem : NUISANCE, bother, pest, irritant, thorn in one's side/flesh, vexation; informal drag, pain, pain in the neck.
arithmetical problems : PUZZLE, question, poser, enigma, riddle, conundrum; informal teaser, brain-teaser.
25B6; adjective a problem child : TROUBLESOME, difficult, unmanageable, unruly, disobedient, uncontrollable, recalcitrant, delinquent.
well behaved, manageable.